Heat exchanger

ABSTRACT

An apparatus for heating water by steam comprises a heat exchanger having a steam chamber. Fluid conduit means directs water through the steam chamber to a hot water outlet chamber. Inlet steam conduit means delivers steam to the chamber. A piston member is located in the water outlet chamber and is movable therein in response to a demand for heated water. The piston member moves to a position in accordance with the desired demand. A blending valve arrangement is utilized in the system so as to continuously blend cold water with hot water exiting from the heat exchange chamber. The blending valve comprises a sleeve valve member which is connected with the piston member and which is movable therewith. The sleeve member has at least one opening therein which cooperates with an opening in an annular baffle in the heat exchanger to control the amount of blending which occurs in accordance with movement of the piston member. In one embodiment, steam is on the heat exchanger at all times, while in other embodiments, a steam inlet valve means located in the steam inlet conduit is controlled by movement of the piston member to apply steam to the heat exchanger only when there is a demand for heated water. In these other embodiments, the piston member is associated with a lever member which pivots upon movement of the piston member. The lever member, when it pivots, controls a valve member which directs fluid to the steam inlet valve means and causes opening of that valve means. Upon return of the piston member to its initial position after the demand for water has been terminated, the lever member is pivoted so as to operate the valve means in the steam inlet conduit to a closed condition. In all embodiments, the fluid conduit means for directing the flow of fluid through the heat exchanger is arranged so as to provide a four-pass system enabling fluid to flow four times through the heat exchange chamber before exiting from the heat exchange chamber.

United States Wilson 1 HEAT EXCHANGER [76] Inventor: Warren M. Wilson, 809 Superior Dr., Huron, Ohio 44839 22 Filed: Apr. 24, 1972 21 Appl. No: 246,622

[52] US. Cl. 165/36, 165/101 [51] Int. Cl. G05d 23/00 [58] Field of Search 165/35, 36, 39, 40, 101

[56] References Cited UNITED STATES PATENTS 2,501,012 3/1950 St. Clair 165/36 Primary ExaminerCharles Sukalo [57] ABSTRACT An apparatus for heating water by steam comprises a heat exchanger having a steam chamber. Fluid conduit means directs water through the steam chamber to a hot water outlet chamber. Inlet steam conduit means delivers steam to the chamber. A piston member is located in the water outlet chamber and is movable therein in response to a demand for heated water. The piston member moves to a position in accordance with the desired demand. A blending valve arrangement is utilized in the system so as to continuously blend cold water with hot water exiting from the heat exchange chamber. The blending valve comprises a sleeve valve member which is connected with the piston member and which is movable therewith. The sleeve member has at least one opening therein which cooperates with an opening in an annular baffle in the heat exchanger to control the amount of blending which occurs in accordance with movement of the piston member. In one embodiment, steam is on the heat exchanger at all times, while in other embodiments, a steam inlet valve means located in the steam inlet conduit is controlled by movement of the piston member to apply steam to the heat exchanger only when there is a demand for heated water. In these other embodiments, the piston member is associated with a lever member which pivots upon movement of the piston member. The lever member, when it pivots, controls a valve member I which directs fluid to the steam inlet valve means and causes opening of that valve means. Upon return of the piston member to its initial position after the demand for water has been terminated, the lever member is pivoted so as to operate the valve means in the steam inlet conduit to a closed condition. In all embodiments, the fluid conduit means for directing the flow of fluid through the heat exchanger is arranged so as to provide a four-pass system enabling fluid to flow four times through the heat exchange chamber before exiting from the heat exchange chamber.

25 Claims, 19 Drawing Figures PATENIEB SEC 3:914

SHEEI 2 OF 8 PATENTED BEE 31974 saw u or a PATENTEU DEC 3 74 SHEET 5 BF 8 PATENTEDBEE 3M4 3.852.147

' SHEETS 0F 8 HEAT EXCHANGER The present invention relates to a heat exchanger, and particularly a heat exchanger for heating water by steam.

There is much prior art in the area of heat exchangers and particularly heat exchangers for heating water by steam. The applicant herein has been active in this field and has obtained prior art Pat. Nos. 3,391,729 and 3,489,205 which disclose heat exchangers of the type in which a member moves in response to a demand for hot water and that member, when it moves, controls the application of steam to the heat exchanger. Moreover, Pat. No. 3,489,205 discloses the blending of cold water with'hot water exiting from the heat exchanger in order to maintain a control of the exiting water temperature.

The present invention provides an improved heat exchanger in 'which a blending of hot water with cold water prior to the water exiting from the exchanger is effected to control exit water temperature. The blending occurs through the'full range of operation of the heat exchanger, and is controlled by a piston member located in the outlet chamber of the exchanger and which moves in a precise manner in response to a demand for heated water.

The blending is accomplished by a fixed aperture which is sufficiently large to assure that water of an apwater temperature may be provided by shifting the moving aperture relative to the fixed aperture.

To cope with the back pressure on the condensate leaving the heat exchanger, the steam supply pressure must be higher than this back pressure. Once the steam supply pressure is established, only the proper characterizing of the cold water bypass or blending is required to achieve temperature control.

Due to the fact that most piping systems are not driptight, if steam is left on the heat exchanger under noflow conditions, it is possible for leaking water to be overheated. Accordingly, the present invention provides a bypass port so that some cold water is mixed with the hot water so that any leaking water would not under these conditions be excessively overheated. The bypass port comes into effect when the piston is in its null or no-flow position.

The exchanger with which the blending is utilized is a four-pass exchanger which is contructed so that the water flows through the heat exchanger in four passes prior to exiting therefrom and prior to the blending op eration. The fourth pass, which is the exiting path, is

centrally located with respect to-the other passes. A

baffle arrangement is provided to separate the passes and direct the water through the heat exchanger. The baffle has the aforementioned fixed aperture which communicates a cold water inlet chamber (defined in part by the baffle) with a centrally located hot water receiving chamber (also defined in part by the baffle) in which the blending or mixing occurs. The steam directed to the heat exchanger may be maintained on the heat exchanger continuously. While allowing the steam to remain on the heat exchanger at all times causes some fouling of the heat exchanger tubes, the heat exchanger of the present invention is constructed with straight tubes which can be readily cleaned.

Alternatively, the system may have an on-off steam control. This would provide no steam during no-flow conditions. In such a system, the piston which moves to control the blending of the hot and cold water in response to demand also controls a valve in the steam pressure line. The valve is of the on-off type and when operated moves to its on-condition in response to a de- .mand for hot water, and the valve is moved to its offcondition when there is no demand. As a result, steam is not on the heat exchanger during stagnant or no-flow conditions, but is only directed to the heat exchanger when there is a demand for hot water. The piston, when in its null or no-flow condition, engages a pin member and holds the pin member against a lever causing the lever to be in a neutral position. The lever is biased so that when the piston member moves, the lever will move under the bias, which movement results in opening of a loader valve which directs fluid to the steam control valve to effect opening thereof. When the pistonmember returns to its no-flow position, the valve or loader is moved to its off-position causing the valve in the steam supply line to be actuated to its off-position. In this embodiment of the present invention, the steam pressure which is delivered to the steam supply valve is directed thereby into the heat exchanger. Such a system is particularly advantageously used where-the low pressure steam is available.

Where high steam pressure is available, a further embodiment of the present invention may be advantageously utilized. In this embodiment, a differential pressure steam valve is provided'in the steam supply I the line 2-2 thereof;

conduit and which is operated in an on-off manner by a loader under the control of a lever similar to that in the embodiment noted above. The differential pressure steam valve operates to reduce the steam pressure so that the desired steam pressure is applied to the heat exchanger. This is effected in an on-off manner so that there is no steam pressure on the unit during no-flow conditions, but upon a demand for hot water, a fixed constant steam pressure is applied to the heat exchanger. The steam pressure in the heat exchanger may remain at a constant value as long as hot water is being utilized. The water temperature is controlled continuously via blending, as in the other embodiments noted above. The loader which controls the steam valve is adjustable to meet installation requirements so that a fixed steam pressure which may be adjusted as desired is applied to the heat exchanger.

Further features of the present invention will be apparent from the following description of specific preferred embodiments thereof made with reference to the accompanying drawings forming a part of this specifi-.

cation and in which:

FIG. 1 is a somewhat schematic elevational view of a heat exchanger embodying the present invention;

FIG. 2 is a top view of the heat exchanger in FIG. 1, looking at the heat exchanger of FIG. 1 as indicated by FIG. 3 is an axial sectional view of the heat exchanger of FIG. 1;

FIG. 4 is a sectional view taken approximately along the line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken approximately along the line 5-5 of FIG. 3',

FIG. 6 is a sectional view taken approximately along the line 6-6 of FIG. 3 with parts removed;

FIG. 7 is a view of a portion of the heat exchanger'of FIG. 3 on a somewhat enlarged scale;

FIG. 8 is a sectional view of the portion of the heat exchanger shown in FIG. 7 and taken approximately along the line 88 thereof;

FIG. 9 is an elevational view looking at the structure of FIG. 7 from the top;

FIG. 10 is a side elevational view of another embodiment of a heat exchanger embodying the present inventron;

FIG. 11 is a top view of the heat exchanger embodiment shown in FIG. 10;

FIG. 12 is a sectional view of a portion of the: heat exchanger shown in FIG. 10;

FIG. 13 is a view of a part of the heat exchanger shown in FIG. 10;

FIG. 14 is a sectional view of a loader device which is used with the embodiment shown in FIG. 10 and taken approximately along line 14-14 of FIG. 11',

FIG. 15 is another view of the loader of FIG. 14 and partly in section;

FIG. 16 is a side elevational view of a further embodiment of a heat exchanger embodying the present invention;

FIG. 17 is a top elevational view of the heat exchanger of FIG. 16; I

FIG. 18 is a sectional. view of a loader, utilized in the embodiment of FIG. 17 and taken approximately along the line l8l8 thereof; and

FIG. His a partial, axial sectional view of the loader of FIG. 18, taken approximately along the line 19-19 thereof.

The embodiment of the present invention illustrated 14. The water is conducted through the heat exchange I chamber 12 by a plurality of fluid conduits and is heated by steam introduced into the heat exchange chamber 12 through a steam inlet 16. The heated water is discharged from the heat exchanger through a water outlet 18. Steam condensate formed in the heat exchange chamber 12 exits therefrom through a steam condensate line 20 located in the bottom of the heat exchanger. The steam condensate line 20 preferably has a steam trap therein which is ventedto the atmosphere so as to prevent the escape of live steam from the heat exchange chamber12.

The heat exchanger 10 includes a housing or shell 28. The housing 28 is preferably of a generally cylindrical shape and has at its upper end a baffle structure 30 (FIG. 3) and at its lower end a baffle structure 31. The baffles 30 and 31 assist in directing the flow of water through the fluid conduits in the heat exchange chamber 12.

The upper baffle 30 is located within an upper shell portion 40 of the heat exchanger and which shell portion 40 supports the outlet 18. On one end of the shell 40 is a flange 42 through which the fasteners 43 extend and secure the shell 40 to the housing 28. At the outer end of the shell 40'is a circular end portion or wall 44 which supports the water outlet 18.

The water to be heated is introduced into the heat exchanger 10 through the water inlet 14 which is in the cylindrical shell 40, as illustrated in FIG. 3. The inlet 14 communicates with an arcuate water inlet chamber 36. The inlet chamber 36 is defined in part by the baffle structure 30 which, as shown in FIG. 5, includes a cylindrical centrally located sleeve 38 co-axially aligned with the shell 40. A pair of radially extending circumferentially spaced plates 46, 48 extend from the sleeve 38. An upper disc portion or ring portion 39, FIG. 3, overlies the perimeter of the baffle 30 and fits within the shell 40. The chamber 36 is defined at its upper end by the portion 39 and at its lower end by the sheet tube or flange 30a formed integrally with the housing 28. The plate portions 46, 48 define the circumferentially spaced sides thereof, and the outer side and bottom are defined by the shell 40 and flange portion 300.

The fluid inlet chamber 36 communicates at its lower end with fluid conduit means 50 which circulates the water to be heated through the heat exchange chamber 12. The water is heated by the steam in the heat exchange chamber 12 as it circulates through the fluid conduit means 50.

The fluid conduit means 50 comprises a substantially circular array of spaced straight conduits or tubular members 62, see FIG. 4. The tubular members 62 are open-ended tubes arranged in circular rows, concentric with the central longitudinal axis of the heat exchange chamber 12, and are supported at their opposite ends by the sheet tubes or flanges 30a and 30!) located at opposite ends of the housing 28. The flanges 30a, 30b also function to prevent steam leakage from the heat exchange chamber 12. i

The water is heated as it flows in parallel paths and in multiple passes through the tubes 62. The water to be heated flows in a first direction through certain of the tubes 62 and in an opposite direction through other tubes 62. The hereinafter-described multiple pass flow of water through the heat exchange chamber 12 permits the chamber 12 to be more compact in length and yet provides sufficient heat exchange surface area between the steam and the water to provide heated water at a predetermined temperature and volume. To provide a flow of water through the tubes 62 in accordance with the present invention, the tubes 62 are divided into four groups of tubes, namely, groups 63, 64, 65 and 66, (FIG. 4). Water flows in a predetermined sequence through the groups of tubes, i.e., first downwardly through the pump 63, upwardly through the group 64, downwardly through the group 65, and upwardly through the centrally located group of tubes 66.

Asnoted above, the baffle structures 30, 31 assist in directing the water through the heat exchanger. The

lower baffle structure 31 (see FIG. 6) includes an outer cylindrical sleeve 52 which is closed at its bottom end ,by a circular plate portion 54. Attached to the end nicat'es with the chamber 12 through an opening 200 in the flange 3011.

Within the lower baffle member is an arcuate chamber 68 located between the cylindrical sleeves 52 and 56. The chamber 68 is in fluid communication with the lower ends of the groups of tubes 63 and 64. Water flowing from the lower or outlet ends of the group of tubes 63 enters the arcuate chamber 68 where it mixes and flows into the lower or inlet ends of the group of tubes 64. The water then flows upwardly through the group of tubes 64 into an arcuate chamber 70 located in the upper baffle 30.

The arcuate chamber 70 is located between the shell 40 and inner sleeve 38 of the upper baffle 30 and is in fluid communication with the upper or inlet ends of the group of tubes 64. The arcuate chamber 70 is operable to mix the water as it flows therein and directs the water flow from the upper ends of the group of tubes 64 into the upper ends of the group of tubes 65. The

and exits into the arcuate chamber 72 formed in the lower baffle structure 31.

The arcuate chamber 72 is located between the cylindrical sleeves 52 and 56. The chamber 72 is in fluid communication with a circular chamber 74 located inside the cylindrical sleeve 56 in the lower annular baffle structure 31. The cylindrical sleeve 56 has a suitable opening 76 therein which provides for the fluid communication between the arcuate chamber 72 and the circular chamber 74. When fluid flows from the lower ends of the group of tubes 65 into the arcuate chamber 72, it is mixed and directed through the opening 76 into the circular chamber 74. The circular chamber 74 is in fluid communication with the lower or inlet ends of the group of tubes 66. Fluid flowing into the circular chamber 74 from the arcuate chamber 72 flows upwardly through the group of tubes 66 into a circular chamber 78 in the upper baffle 30, which chamber 78 is formed within the inner cylindrical sleeve 38.

It should be apparent from the above that the water flows through the heat exchange chamber 12 in a predetermined sequence. The water flows first through the outwardly disposed groups of tubes 63, 64, and 65 and located in the heat exchange chamber 12 and then through the inwardly disposed group of tubes 66. As a result, the water flows in four passes through the heatexchange chamber before exiting therefrom.

It should be noted that as the water flows into the chambers defined by the baffle structures and 31, the water from each .tube 62 of a group of tubes is mixed with water from the other tubes of the same group of tubes to provide even heating of the water. Thus, if for some reason the tubes 62 are not being evenly heated, the mixing of the water when it flows into the baffle chambers will compensate for any uneven heating of the tubes 62 that is taking place.

The flow of fluid from the heat exchanger 10 through the outlet 18 thereof is controlled by the demand for heated water. The outlet 18 is connected with a faucet or some other type of valve mechanism which is opened when there is a demand for heated water. The degree of opening of the faucet is under the control of the user of the water and the wider the opening, the greater the demand. Located in the shell 40 is a piston member 100 (FIG. 3). The baffle member 30 is removable from the shell 40 for assembly of the piston 100.

The piston member divides the shell 40 into two chamber portions 101 and 102. The chamber portion 102 includes the annular baffle 30. When the faucet or valve which controls the demand for fluid is closed, the pressure of fluid in the chamber portions 101 and 102 acting on the piston 100 is substantially equal so that the piston 100 takes the position shown in FIG. 3 in which it is biased to its null or no flow position by a spring 110.

When the faucet or valve connected with the outlet 18 is opened, the pressure in the upper chamber portion 101 is reduced, and as a result in the piston 100 begins to move upwardly against the bias of the spring 110. When this movement occurs, a valve mechanism,

' generally designated 111, opens and allows fluid flow from the central chamber portion 78 defined by the sleeve 38 through the outlet 18. The flow provides a pressure drop across the piston 100 which enables the piston to take a position depending upon demand. As an alternative to the flow through the piston and the valve mechanism 111, a slot could be provided in the' inner wall of the shell 40 and through which the flow is controlled by the piston 100.

The valve mechanism 111 comprises a flow tube member 112 which is substantially secured to the piston 100 so as to move therewith. The flow tube member 112 has a conical end portion or bore 116 therein. The flow tube 112 comprises one part of the valve mechanism, whereas the other valve member of the valve mechanism 111 is a disc member 120 which is located in the flow tube member 112. The flow tube member 112 has an elongated extent and extends into a rotary joint member 124 and in which the flow tube member 112 is slidable. The rotary joint 124 is suitable located in an opening in the wall 44 of the shell 40. A suitable seal 124b is located and positioned so as to prevent leakage of fluid between the wall opening and the rotary joint member 124.

When the piston member 100 moves upwardly in the shell 40, the extension 121 moves upwardly in the rotary joint member 124. A suitable pin is carried by the rotary joint member 124 and is located so as to be received in a slot 131 in the elongated projection 121 so that as the projection moves vertically upwardly the movement thereof is restricted to a linear movement.

As the member 112 moves vertically upwardly, the valve member 120 does not move vertically. The valve member 120 is connected with a stem 135, which stem in turn is secured to aspider member 136 which has suitable openings so that water may flow therepast. As the member 112 moves vertically relative to valve member 120, the degree of opening of the valve mechanism 111 changes, since as the member 112 moves vertically, the space between the valve disc 120 and the bore 116 in the member 1 12 varies in proportion to the extent of movement of the piston member 100. Accordingly, depending upon the amount of movement of the piston 100, the amount or volume of fluid or flow rate of fluid from the exchanger is controlled thereby.

ton 100 and the blending is continuous over the entire range of operation of the unit. In order to effect this blending, a bypass blending valve arrangement, generally designated I70 and shown in detail in FIGS. 7-9, is provided for directing a controlled flow of cold water directly from the inlet chamber 36 to the outlet chamber 78 centrally located in the baffle 30. To this end, the annular baffle portion 38 has an opening 171 therein which is in communication with the inlet chamber 36 for cold water. In addition, a valve sleeve member 175 is secured by suitablemeans to the piston member 100 and projects downwardly into the baffle 38. The sleeve member 175, accordingly, moves with the piston member 100. The valve sleeve 175 has a close fit with sleeve portion 38, which minimizes uncontrolled-flow of cold water. Only a slight clearance is necessary between the valve sleeve 175 and baffle portion 38 to minimize leakage, since there is only a The sleeve member 175 has an opening 17'! therein. The opening 177 is shaped so as to control the amount of blending of cold water with the hot water in accordance with the movement of-the piston member 100 so that the desired outlet water temperature is produced. The particular-shape of the openings can be varied to meet conditions and specifications.

To cope with back pressure on the condensate leaving the heat exchanger, the steam supply pressure must be greater than that back pressure. Once the steam supply pressure is established, the opening I77 can be shaped to provide the desired temperature control. In addition, as will be described hereinbelow, the opening 177 can be adjusted so as to ing.

As the piston member 100 moves vertically upvary the amount of blend- 177C therewith. The surface 177d interconnects with a surface 177.? which is also vertically extending and terminates at the surface 177:].

' The sleeve member 175 is located concentrically with respect to the sleeve 112 of valve mechanism 11 I, and the sleeve 112 and piston member 100 in turn are located concentrically within the circular shell 40. As a result, the piston member 100 can be rotated within the shell in order to rotate the sleeve 175 and its opening 177 relative to the opening 171 in the baffle portion 38. As a result of the rotation of the opening 177, an adjustment of the amount of blending can be effected, as desired. This should be apparent, since by rotating the sleeve 175 to a given position, a different area of overlap of the openings will occur upon vertical movement of the sleeve 175.

The bolts 179 are threaded into the wall 44 and hold cap member 179a on the wall 44. Specifically, member 179a engages the rotary joint member 124 which in turn engages springlll) at its end opposite the end which engages piston. 100. By tightening the bolts 179, the force the spring 110 applies to the piston 100 increases. By loosening the bolts 179, the spring force on wardly, the opening 177 uncovers a varying area of opening 171 for purposes of directing of cold water from the inlet chamber 36 to the chamber 78 in the heat exchanger.

It should be apparent that the shape of the opening 177 and arrangement of parts, as shown in FIG. 7, is such that on initial movement a portion of the opening 177 which has a substantially common circumferential extent with the opening 171 aligns with the opening 171. Accordingly, at low flow rates a substantially large percentage of cold water is blended with the hot water exiting from the heat exchange tubes 66. The greater the distance of movement of the piston 100, however, the lesser the percentage of cold water being blended with the hot water, as should be apparent due to the continuously reducing size of the opening 177. At the maximum flow rate of the system, the lowest percentage of cold water is blended with the hot. However, it

should be emphasized that blending occurs throughout the piston 100 is reduced.

While the above-described embodiment utilizes a single opening in the sleeve 175, it is possible that a plurality of separate discrete openings could be provided in the sleeve 175 where each opening provides variable blending characteristics as desired.

As illustratedin the drawings, there is a portion or space, generally designated 180 in FIG. 7, between the upper surface [770 of the opening 177 and the lower surface defining the opening 171. This space may be termed a lap space. Of course, it should be apparent there is no blending occurring when the sleeve I moves through that space, since there is no alignment of the opening 177 with any portion of the opening 171. However, there is also' no outlet water flow from the heat exchanger, since the valve 111 is not yet opened. The space 180 is sized so that the blending begins when outlet flow begins.

Also, as shown in FIGS. 8 and 9, when the piston member is in its lowermost or null position, a small opening 181 in the sleeve member overlaps or communicates with the opening 171 in the sleeve 38. The opening 181 provides for a slight blending of cold water from the inlet chamber 36 into the hot water outlet chamber 78 inthe event of water leakage occurring from the heat exchanger. This has a substantial advantage in reducing the temperature of any water which may leak through the faucet or outlet from the heat exchanger. Such blending is important if steam is on the heat exchanger when in a no-flow condition which would result in extremely hot water exiting from the heat exchanger in the event of such leakage. The blending in such no-flow conditions ensures that extremely hot water does not leak through the outlet.

As is well known, leaving the steam pressure on a heat exchanger during no-flow conditions can result in fouling of the heat exchanger and in order to minimize the fouling of the heat exchanger, it is preferable to cut off the steam pressure in the heat exchanger under noflow conditions. The embodiment of the present invention, which is illustrated in FIGS. 10 and 11 and which has all of the features described hereinabove in connection with the embodiments of FIGS. 1-9, provides for a shut-off of the steam to the heat exchanger during noflow conditions. The embodiment shown in FIGS. 10 and 11 is particularly adaptable for use with a low pressure steam supply source and the steam is directed to the heat exchanger in an on-off manner, as will be described hereinbelow.

In the embodiment of FIG. 10, a steam valve 200 is located in the steam supply conduit and the steam valve 200 has an on-position for directing the steam pressure received by it into the heat exchange chamber 12. The steam valve 200 also has a closed position for blocking any flow of steam into the heat exchanger. A control mechanism, generally designated 201, controls the actuation of the valve 200 and specifically controls the actuation of the valve 200 upon movement of the piston member 100.

It should be clear that the piston 100 comprises a member which is located internally of the heat exchanger and moves therein in response to a demand for heated water. The control mechanism 201 includes a pin 202 (FIG. 12) which has an upper surface which abuts the undersurface of the piston 100 at 203 when the piston 100 is in its null or no-flow position. The pin 202 is slidable in a suitable guide member 204 suitably supported in the shell 40, and specifically secured to the portion 39 of the baffle which is provided with an opening 204a for receiving the guide 204. The lower end of the pin 202 engages, as shown in FIG. 12, a lever member 205. The lever member 205.is supported for pivotal movement by a fulcrum member 206 pressfit in a housing 207 (See FIG. 14). The outer end of the lever member 205 is located in a casing 208 which is connected with the'housing 207. The housing 207 is suitably supported on sleeve portion 40 of the heat ex.- changer. A spring 210 in the casing 208 has a lower end acting on the lever member 205 tending to pivot the lever 205 clockwise about its fulcrum, as shown in FIG. 14. The spring 210 at its upper end abuts a nut 212.

The casing 208 and housing 207 may be bodily removed from the shell 40 along with the lever 205 by simply releasing any suitable connectors holding the housing 207 on the shell 40. In the event that this disassembly does occur, the pin 202 will not fall from the guide 204 due to a spring clip 204b which encircles the upper end of the pin 202 and would prevent any falling movement of the pin 202. Reassembly may be effected by merely inserting lever 205 into the shell 40 into abutment with the lower end of pin 202 and resecuring the housing 207 to the shell 40.

The piston member 100, when in its lower position, as shown in FIG. 12, holds the lever member 205 in the position shown and prevents the spring 210 from moving the outer end of the lever member downwardly. However, if the piston member 100 moves vertically upwardly. the spring 210 causes the outer end of the lever member 205 to move downwardly (clockwise about fulcrum 206).

The outer end of the lever member 205 carries a screw member 215. The screw member 215 on its lower end has a ball 216 attached thereto in any suitable manner. The ball comprises a valve member which controls the flow of fluid past a valve seat 217 for the ball valve member. When the lever member 205 is in its null or no-flow position, the ball 216 is in engagement with the valve seat 217 and prevents the flow of fluid therepast. When the lever member 205 is moved downwardly, the ball 216 moves downwardly relative to the valve seat 217 and allows for flow of fluid therepast.

The ball member 216, when moved downwardly, is moved in a guide portion 220 of a nut 221 which is secured in the lower end of the casing 208. The nut 221 has a bore or passage 222 therein connecting the lower end of the ball 216 to drain. When the ball member 216 is moved downwardly sufficiently, it will block fluid flow through the drain 222. This movement occurs as the piston 100 and sleeve 175 move through the lap distance 180.

The housing member 207 which encircles the lever 205 is suitably connected at its end adjacent the shell 40 with a connector portion 230 of the shell 40 and which has an opening 231 therein. The opening 231 communicates with chamber 36, which, as noted above, is the cold water inlet chamber. The housing 207 being hollow directs the cold water inlet pressure into the chamber 232 located above the ball member 216, as shown in FIG. 14. This flow is through the top of the fulcrum support member 206 which is open. When the ball member 216 moves downwardly and blocks drain 222, the fluid pressure in the chamber 232 .an outlet 233 in the casing 208 and through the conduit 235 to the valve 200.

As noted above, there is an initial or lap movement of the piston which must occur before the valve mechanism 111 opens to direct fluid from the heat ex changer. The lap movement of the pistonis such that the ball valve 216 will be moved off its seat 217 and block drain 222 so that practically simultaneously with the beginning of outlet flow, steam will be applied to the exchange chamber 12. Accordingly, the pressure will remain on the exchanger until water outlet flow ceases and the piston returns to its null position.

The valve 200 is a conventional valve which is moved to its fully open position upon pressure being applied thereto and moves to its fully closed position when the pressure is released. The valve 200 preferably is springbiased closed and opened by the pressure acting against the spring. Accordingly, location of the ball 216, as described above, sealing the drain 222 and directing pressure from chamber 232 to the valve 200 causes the valve 200 to open and steam to be applied to the heat exchange chamber 12. Accordingly, upon a demand for water the piston 100 moves vertically upwardly, as shown'in FIG. 12, and through the action of the lever 205 and the valve 216 fluid pressure is applied to the valve 200 causing opening thereof and steam to be applied to the heat exchanger. At the same time, fluid may flow from the heat exchanger, since the valve mechanism 111 has been opened in dependence upon the demand requirements. The system is constructed so that the valve 200 operates as an on-off valve and the valve 200 is returned to its off-position cutting off the supply of steam to the exchange chamber when the piston 100 moves back to its null or no-flow position. When the piston returns to its null position, the undersurface thereof engages the upper surface of the pin 202. When this engagement occurs, the piston 100 causes the lever 205 to pivot against the bias of the spring 210 pushing the ball member 216 back into sealing engagement with the valve seat 217.

Moreover, adjustment of the spring by bolts 179 ensures that the loader valve 200 is shut off when the piston is in neutral. It should be apparent that the greater the force applied to lever 205 by spring 210, the greater the force necessary to move the ball 216 back to its seat, and accordingly the greater the force required to be applied to the piston 100 by spring 110. When the ball member 216 seals against valve seat 217, the outlet 222 in the casing 208 is connected to the drain. As a result, the actuator for valve 200 is connected with drain and the valve 200 returns to its closed position blocking steam flow to the exchange chamber 12.

In the event that the source of steam is a high pressure steam source capable of supplying substantial steam pressure to the heat exchange chamber, strictly an on-off steam valve, as in the low pressure embodiment of FIGS. -15, may not be sufficient in order to properly control the steam pressure, but rather a reducing valve, which reduces the steam pressure, should be utilized with the heat exchanger mechanism described in connection with FIGS. 1 to 9. The embodiment of the present invention shown in FIGS. 16-19 provides a control for the application of steam to the heat exchange chamber through such a pressure-reducing valve 300.

The valve 300 may be operated in an on-off manner to provide a constant steam pressure to the heat exchange chamber. The valve 300 is a conventional pressure-reducing valve and has a diaphragm, one side of which is loaded by the pressure in the heat exchange chamber through a conduit 301 and the other side of which is provided with a water pressure through a conduit 302. The water pressure through conduit 302 is controlled by a control mechanism or loader device, generally designated 305. The loader device 305 is operated under the control of the piston 100, pin 202, and lever 205 much in the manner described in connection with FIGS. 14 and 15. However, the loader device as specifically shown in FIGS. 18 and 19 is of a somewhat different construction than that in FIGS. 14, 15.

The loader device 305, shown in FIGS. 18 and 19 includes a spring 310 which acts on a plate or flange member 311 which is connected to a screw member 312 carried by the lever 205. When the piston member 100 moves upwardly away from the lever 205 and pin 202, spring member 310 biases the screw 312 downwardly and moves the end of the lever which it engages wardly. The stem 314 engages a valve seat 315 which I is connected with the upper side of a diaphragm member 316 and the diaphragm member 316 on its lower side carries a valve seat 317 which engages a valve stem 318. When the plate 313 moves downwardly, the diaphragm 316, valve seat 317 and valve stem 318 also move downwardly. The lower end of the valve stem 318 carries a valve member 320 which engages with a valve seat 3200 and, when moved downwardly, moves away from the valve seat 320a and effects opening for fluid flow between the valve member 320 and the valve seat 3200 which it normally engages and against which it is biased by a spring 321.

When the valve member 320 moves downwardly away from the valve seat 3200, fluid pressure from the inlet chamber 36 is communicated through the housing 207 and through a conduit 325 into a passageway 326 and past the valve member 320 into a conduit 327. The conduit 327 communicates with an outlet 328 which in turn communicates with the conduit 302 for directing the pressure to the pressure-reducing valve 300. The pressure in the pressure-reducing valve 300 increases in a continuing manner until the valve member 320 moves to a closed position in engagement with its valve seat 320a.

The valve member 320 moves into a-closed position in engagement with its valve seat 320a when the stem member 318 moves upwardly, or is allowed to move upwardly under the bias of the spring 321. This occurs when the diaphragm member 316 moves upwardly. The diaphragm member divides a chamber into two chamber portions 330 and 331. The chamber portion 330 communicates with the conduit 327 and as the pressure in the valve 300 increases, the pressure in chamber portion 330 also increases, tending to move the diaphragm member 316 vertically upwardly, as shown in FIGS. 18 and 19.

When the pressure built up in chamber 330 is sufficient to overcome the bias of the spring 310, the diaphragm member 316 will move vertically upwardly and the valve member 317 and steam 318 will follow the movement of that diaphragm member. The movement eventually will cause a closing of the valve 320 with pressure in the valve 300 and in the chamber portion 330 being substantially equal.

Accordingly, the outlet pressure of the loader 305 is controlled by the bias applied to the spring 310, since the spring 310 must be overcome by the diaphragm 316 which is moved back to its initial position by the pressure in chamber 330. The bias on the spring 310 is adjustable by turning a screw 336, which, when threaded within a housing portion 337, causes a greater bias to be applied to the spring 310. When proper adjustment is made, cap 335 and gasket 335a seals and locks adjustment stem 336. The greater the bias applied to the spring 310, the greater the force which is necessary in chamber 330 to return the diaphragm to its neutral position to effect the closing of the valve 320. Accordingly, the greater the bias on the spring 310, the greater the pressure required in the spring 310 and in the chamber 330 to return the diaphragm and valve member 320 to its closed position.

When the piston member returns to its neutral or null position, the lever member 205 is moved upwardly so that the screw 312 which has an abutting engagement with the plate 313 is moved upwardly out of contact with the plate 313. As a result, spring 338 moves the valve member 314 upwardly away from its valve seat 315 which in turn enables the spring-biased diaphragm to move upwardly under the pressure in chamber 330 away from the valve member 317.

As a result of these relative sequential movements, the valve member 317 and the valve member 316 are out of engagement with their valve seats simultaneously. The upper chamber portion defined by the diaphragm 331 is in contact with drain through outlet 339. Since the valve members 315 and 317 are out of contact with their valve seat simultaneously, the pressure in chamber 330, and likewise in valve 300, is communicated past the values 317 and 315 through the outlet conduit 339 to drain. As a result, the valve member 300 is returned to its neutral or closed position and the valve member 300 blocks the flow of steam to the heat exchanger 12.

Adjustement of screw 336 changes the bias on spring 310 and effectively determines the loader pressure output to be imposed on valve 300 in an on-of manner dictated by the piston 100. Bias of spring 338 and spring 321 is fixed. The loader 305 is identical to a conventional reducing/relief valve mechanism except for the mode of automatic operation via the piston 100 and lever 205.

It should be apparent from the above, that the embodiment of the present invention described in FIGS. 15-19 does include a loader 305 which operates in an on-off manner. The loader is adjustable, however, in order to control the outlet pressure applied to the steam inlet valve 300. Moreover, the steam inlet valve is of the pressure-reducing type in that it senses both the pressure directed to it from the loader 305, as well as the steam pressure in the heat exchanger. Accordingly, the system can, through appropriate adjustment, be controlled so that a given constant inlet steam pressure is provided on the heat exchanger, which is substantially lower than the steam pressure delivered to the valve 300 from the steam supply.

Viewing FIG. 3, it is clear that valve member 120 is adjustable vertically via threaded stem 135 in spider 136 in which it is threadably engaged. Lock nut 135a holds this adjustment. At the null or no-flow position of piston 100, the vertical position of flow tube 112 is fixed. Therefore, adjustment of stem 135 determines the lap", or movement required of piston 100 before actual flow takes place. This movement is abrupt and ideally suited to on-off type of control, which is used by either loader 201 or 305.

Member 124 is, as noted, a rotary joint, which permits 360 rotation of the piston assembly via a rod insert in apertures 1240 spaced at 60 intervals. This adjustment is relatively stiff due to friction, and once made will remain fixed. Thus, with properly characterized sleeve valve member 175, the discharge temper-. ture of the water can be changed externally. Once an adjustment is made, pin 130 in member 124 operating in slot 131 permits only vertical movement of the piston assembly and sleeve 175.

The bias of spring 110 is adjusted by nuts 179, and in addition to returning piston 100 to its null point, is strong enough to operate lever 205 against the bias of the loader spring and insure turning off the steam to the heat exchanger when no-flow of water occurs. This adjustment is made once at start-up'and left fixed.

In view of the foregoing, it should be clear that applicant has provided a practical, efficient and novel construction of a heat exchanger system, and that certain modifications, changes, and adaptations maybe made therein.

What l claim is:

1. Apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a member located in said water outlet chamber and movable therein in response to a change in the demand for hot water, and bypass valve means controlled by,movement of said member for continuously directing some cold water to said outlet chamber without flowing through said fluid conduit means so as to continuously mix with heated water during flow conditions.

2. An apparatus as defined in claim 1 wherein said bypass valve means includes a relatively fixed valve part and a second valve part carried by said member, and said valve parts having cooperable openings which provide a variable flow depending on the extent of member movement.

3. An apparatus as defined in claim 2 wherein said member is of a generally cylindrical shape and is rotatable within said water outlet chamber to adjust the position of the opening in said second valve part relative to the opening in the first valve part and thereby adjusts the amount of mixing of cold water with heated water upon movement of the member.

4. An apparatus as defined in claim 1 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam chamber in four passes, said fluid conduits comprising first, second and third groups disposed outwardly from the center of the heat exchange chamber and a fourth group of fluid conduits which is located centrally of the heat exchange chamber and surrounded by the first, second and third groups, said fourth group of fluid conduits directing the flowof fluid from the outlet thereof into the water outlet chamber portion into which the bypass valve means directs cold water.

5. An apparatus as defined in claim 4 further including a pair of annular baffles, one of the annular baffles being located at each end of the groups of conduits, the one annular baffle defining in part said inlet chamber which communicates with the inlet ends of the first group of conduits, the other annular baffle defining in part a chamber communicating with the outlet end of the first group of fluid conduits and the inlet end of the second group of fluid conduits, said first annular baffle defining a chamber communicating with the outlet of the second group of fluid conduits and the inlet ends of the third group of fluid conduits, and said other annular baffle defining a chamber communicating the outlet of the third group of fluid conduits with the inlet of the fourth group of fluid conduits.

6. An apparatus as defined in claim 1 wherein said member has a no-flow position from which it moves in response to a demand for hot water, and means for directing cold water to said outlet chamber when said piston member is in its no-flow position to minimize the temperature of water leakage therefrom.

7. An apparatus as defined in claim 1 further includ- .ing a steam valve for controlling the application of steam pressure to said steam chamber, means for actuating said steam valve in response to movement of said member, said means including a pin member engageable with the member and movable upon movement of the member and a lever member operatively connected with the pin member and pivotal upon movement of the member, and means operatively interconnecting said lever member and said steam valve for controlling said steam valve upon movement of said lever.

8. An apparatus as defined in claim 7 wherein said means operatively interconnecting the lever member and ,said steam valve comprises a valve means which is opened upon movement of said lever member and which when opened directs water pressure from said inlet chamber to said steam valve.

9. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a member movable from a no-flow position in response to a demand for hot water. and bypass valve means controlled by movement of said member for directing some cold water to said outlet chamber without flowing through said fluid conduit means so as to mix with heated water during a flow condition, and means for directing coid water to said outlet chamber when said member is in its no-flow position to minimize the temperature of any water leakage therefrom.

10. An apparatus as defined in claim 9 wherein said bypass valve means comprises a relatively fixed valve part and a second valve 'part carried by said member,

said valve parts have cooperable first and second openings respectively which provide a variable area of flow depending upon the extent of piston movement, and said means for directing cold water to said outlet chamber when said member is in its no-flow position comprises a third opening in said second valve part which directs cold water to said outlet chamber when said first and second openings are not overlapping.

11. An apparatus as defined in claim 9 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam chamber in four passes, said fluid conduits comprising first, second and third groups disposed outwardly from the center of the heat exchange chamber and a fourth group of fluid conduits which is located centrally of the heat exchange chamber and surrounded by the first, second and third groups, said fourth group of fluid conduits directing the flow of fluid from the outlet thereof into the water outletchamber portion into which the bypass valve means directs cold water.

12. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber; said fluid conduit means including at least four sets of conduits for directing the water through the steam chamber in four passes, at least one of said conduits directing the water. into the outlet chamber, inlet steamconduit means for delivering steam to said steam chamber, a piston member located in said water outlet chamber and movable therein in response to a change in the demand for heated water, bypass valve means for directing some cold water to, said outlet chamber without flowing through said fluid conduit means so as to mix with heated water, said bypass valve means including a relatively fixed sleeve-like valve part and a second sleevelike valve part carried by said piston, said second] sleeve-like valve part being concentrically arranged with the piston, and said valve parts having cooperable openings which provide a variable area of flow depending on the extent of piston movement.

13. An apparatus as defined in claim 12 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam cham-.

into the water outlet chamber portion into which the bypass valve means directs cold water.

14. An apparatus as defined in claim 12 further including a steam valve for controlling the application of steam on said heat exchanger, said steam valve having an open position for directing steam pressure to the steam chamber and a closed position blocking steam pressure being applied to the steam chamber, said steam valve being moved from its open position to its closed position in response to water pressure being applied thereto, control valve means for directing water pressure to said steam valve, and means for opening said control valve means in response to movement of said-piston member.

15. An apparatus as defined in claim 14 wherein said control valve means has a hollow housing portion communicating with said water inlet chamber and a lever extending from said piston member through said hollow housing portion, a valve member operatively associated with the lever member and which is opened upon movement of the lever member in one direction and which is closed upon movement of the lever member in the opposite direction.

16. A heatexchanger for heating a first fluid by a second fluid comprising a heat exchange chamber for receiving the second fluid, a first group of fluid conduit means for directing the first fluid through said heat exchange chamber in a first direction, a second group of fluid conduits for directing the first fluid through said heat exchange chamber in a second direction opposite said first direction after the first fluid has exited from said first fluid conduits, a third group of fluid conduits for directing the first fluid through said heat exchange chamber in the first direction after the first fluid has exited fromsaid'second fluid conduits, a fourth group of fluid conduits for directing the first'fluid through said heat exchange chamber in the second direction after the first fluid has exited from said third group of fluid conduits, said first, second and third groups of fluid conduits being disposedoutwardly from the center of said heat exchange chamber, said fourth group of fluid conduits being located centrally of said heat exchange chamber and surrounded by said first, second and third groups of fluid conduits, annular baffle means for directing the flow of said first fluid sequentially between said first, second, third and fourth groups of fluid conduits and blocking the flow of said first fluid between other of said groups of conduits said annular baffle means including a pair of annular baffles, one of said annular baffles being located at one end of said groups of fluid conduits, and the other of said annular baffles being located at the opposite end of said groups of fluid conduits, said one annular baffle including a first chamber in fluid communication with said first group of fluid conduits, a second chamber in fluid communicawith said second and third groups of fluid conduits and a third chamber in fluid communication with said fourth group of fluid conduits and wherein said plurality of chambers are operable to direct the flow of said first fluid through said groups of fluid conduits in predetermined sequence, said other annular baffle including a first chamber in fluid communication with said first and second groups of conduits, a second chamber in fluid communication with said third group of fluid conduits, and a third chamber in fluid communication with said fourth group of fluid conduits, outlet means for directing the first fluid from said heat exchange chamber and communicating with said third chamber of said one annular baffle.

17. A heat exchanger as defined in claim 16 further including bypass means for bypassing the flow of fluid from said first chamber of said one annular baffle in order to mix cold water with hot water exiting therefrom.

18. A heat exchanger as defined in claim 16 further including a member movable in response to a demand for said first fluid, and valve means operatively connected with said member and actuated thereby to effect a flow of the first fluid into the outlet chamber which bypasses said fluid conduit means so that cold first fluid is blended with heated first fluid under control of said member.

19. A heat exchanger as defined in claim 18 wherein said member has a no-flow position in which said valve means is closed and means for directing cold water from said first chamber of said one annular baffle to said third chamber of said one annular baffle when said means is in its no-flow position.

20. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a hot water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a piston member located in said hot water outlet chamber and movable therein in response to a demand for hot water, steam valve means in said inlet steam conduit means for controlling flow of steam into said steam chamber, means for actuating said valve means in response to movement of said piston member, said means including a pin member engageable with said piston member and movable upon movement of the piston member in response to said demand, a lever operatively connected with said pin member and pivotal upon movement of said piston member. and means operatively interconnecting said lever member and said steam valve means for controlling said steam valve means upon movement of said lever.

21. An apparatus as defined in claim 20 wherein said means operatively interconnecting the lever member and steam valve means comprises a control valve operated by said lever member and for directing water pressure to said steam valve to effect opening of the steam valve upon opening of the control valve.

22. An apparatus as defined in claim 21 wherein said control valve has means for communicating inlet water pressure thereto and when opened directs said pressure to said steam valve to effect opening thereof.

23. An apparatus as defined in claim 22 wherein said valve is spring-biased by a first spring means to an open position for directing water pressure to said steam valve means and said piston member through said lever moves said valve means to said closed position and second spring means acting on said piston member urging said piston member to its no-flow position in which said control valve is in its closed position, and means for adjusting said second spring means which acts on said piston.

24. An apparatus as defined in claim 20 wherein said means operatively interconnecting the lever member and steam valve means comprises a control valve operated by said lever member for directing an adjustable fluid pressure to said steam valve to effect opening of the steam valve upon opening of the control valve.

25. An apparatus as defined in claim 24 wherein said steam valve is a differential diaphragm type so that the adjustablefluid pressure produces an adjustable steam pressure to the heat exchanger. 

1. Apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a member located in said water outlet chamber and movable therein in response to a change in the demand for hot water, and bypass valve means controlled by movement of said member for continuously directing some cold water to said outlet chamber without flowing through said fluid conduit means so as to continuously mix with heated water during flow conditions.
 2. An apparatus as defined in claim 1 wherein said bypass valve means includes a relatively fixed valve part and a second valve part carried by said member, and said valve parts having cooperable openings which provide a variable flow depending on the extent of member movement.
 3. An apparatus as defined in claim 2 wherein said member is of a generally cylindrical shape and is rotatable within said water outlet chamber to adjust the position of the opening in said second valve part relative to the opening in the first valve part and thereby adjusts the amount of mixing of cold water with heated water upon movement of the member.
 4. An apparatus as defined in claim 1 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam chamber in four passes, said fluid conduits comprising first, second and third groups disposed outwardly from the center of the heat exchange chamber and a fourth group of fluid conduits which is located centrally of the heat exchange chamber and surrounded by the first, second and third groups, said fourth group of fluid conduits directing the flow of fluid from the outlet thereof into the water outlet chamber portion into which the bypass valve means directs cold water.
 5. An apparatus as defined in claim 4 further including a pair of annular baffles, one of the annular baffles being located at each end of the groups of conduits, the one annular baffle definIng in part said inlet chamber which communicates with the inlet ends of the first group of conduits, the other annular baffle defining in part a chamber communicating with the outlet end of the first group of fluid conduits and the inlet end of the second group of fluid conduits, said first annular baffle defining a chamber communicating with the outlet of the second group of fluid conduits and the inlet ends of the third group of fluid conduits, and said other annular baffle defining a chamber communicating the outlet of the third group of fluid conduits with the inlet of the fourth group of fluid conduits.
 6. An apparatus as defined in claim 1 wherein said member has a no-flow position from which it moves in response to a demand for hot water, and means for directing cold water to said outlet chamber when said piston member is in its no-flow position to minimize the temperature of water leakage therefrom.
 7. An apparatus as defined in claim 1 further including a steam valve for controlling the application of steam pressure to said steam chamber, means for actuating said steam valve in response to movement of said member, said means including a pin member engageable with the member and movable upon movement of the member and a lever member operatively connected with the pin member and pivotal upon movement of the member, and means operatively interconnecting said lever member and said steam valve for controlling said steam valve upon movement of said lever.
 8. An apparatus as defined in claim 7 wherein said means operatively interconnecting the lever member and said steam valve comprises a valve means which is opened upon movement of said lever member and which when opened directs water pressure from said inlet chamber to said steam valve.
 9. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a member movable from a no-flow position in response to a demand for hot water, and bypass valve means controlled by movement of said member for directing some cold water to said outlet chamber without flowing through said fluid conduit means so as to mix with heated water during a flow condition, and means for directing cold water to said outlet chamber when said member is in its no-flow position to minimize the temperature of any water leakage therefrom.
 10. An apparatus as defined in claim 9 wherein said bypass valve means comprises a relatively fixed valve part and a second valve part carried by said member, said valve parts have cooperable first and second openings respectively which provide a variable area of flow depending upon the extent of piston movement, and said means for directing cold water to said outlet chamber when said member is in its no-flow position comprises a third opening in said second valve part which directs cold water to said outlet chamber when said first and second openings are not overlapping.
 11. An apparatus as defined in claim 9 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam chamber in four passes, said fluid conduits comprising first, second and third groups disposed outwardly from the center of the heat exchange chamber and a fourth group of fluid conduits which is located centrally of the heat exchange chamber and surrounded by the first, second and third groups, said fourth group of fluid conduits directing the flow of fluid from the outlet thereof into the water outlet chamber portion into which the bypass valve means directs cold water.
 12. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a water outlet chamber, said fluid conduit means including at least four sets of conduits for directing the water through the steam chamber in four passeS, at least one of said conduits directing the water into the outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a piston member located in said water outlet chamber and movable therein in response to a change in the demand for heated water, bypass valve means for directing some cold water to said outlet chamber without flowing through said fluid conduit means so as to mix with heated water, said bypass valve means including a relatively fixed sleeve-like valve part and a second sleeve-like valve part carried by said piston, said second sleeve-like valve part being concentrically arranged with the piston, and said valve parts having cooperable openings which provide a variable area of flow depending on the extent of piston movement.
 13. An apparatus as defined in claim 12 wherein said fluid conduit means includes at least four sets of conduits for directing the water through the steam chamber in four passes, said fluid conduits comprising first, second and third groups disposed outwardly from the center of the heat exchange chamber and a fourth group of fluid conduits which is located centrally of the heat exchange chamber and surrounded by the first, second and third groups, said fourth group of fluid conduits directing the flow of fluid from the outlet thereof into the water outlet chamber portion into which the bypass valve means directs cold water.
 14. An apparatus as defined in claim 12 further including a steam valve for controlling the application of steam on said heat exchanger, said steam valve having an open position for directing steam pressure to the steam chamber and a closed position blocking steam pressure being applied to the steam chamber, said steam valve being moved from its open position to its closed position in response to water pressure being applied thereto, control valve means for directing water pressure to said steam valve, and means for opening said control valve means in response to movement of said piston member.
 15. An apparatus as defined in claim 14 wherein said control valve means has a hollow housing portion communicating with said water inlet chamber and a lever extending from said piston member through said hollow housing portion, a valve member operatively associated with the lever member and which is opened upon movement of the lever member in one direction and which is closed upon movement of the lever member in the opposite direction.
 16. A heat exchanger for heating a first fluid by a second fluid comprising a heat exchange chamber for receiving the second fluid, a first group of fluid conduit means for directing the first fluid through said heat exchange chamber in a first direction, a second group of fluid conduits for directing the first fluid through said heat exchange chamber in a second direction opposite said first direction after the first fluid has exited from said first fluid conduits, a third group of fluid conduits for directing the first fluid through said heat exchange chamber in the first direction after the first fluid has exited from said second fluid conduits, a fourth group of fluid conduits for directing the first fluid through said heat exchange chamber in the second direction after the first fluid has exited from said third group of fluid conduits, said first, second and third groups of fluid conduits being disposed outwardly from the center of said heat exchange chamber, said fourth group of fluid conduits being located centrally of said heat exchange chamber and surrounded by said first, second and third groups of fluid conduits, annular baffle means for directing the flow of said first fluid sequentially between said first, second, third and fourth groups of fluid conduits and blocking the flow of said first fluid between other of said groups of conduits said annular baffle means including a pair of annular baffles, one of said annular baffles being located at one end of said groups of fluid conduits, and the other of said annular baffles being located at The opposite end of said groups of fluid conduits, said one annular baffle including a first chamber in fluid communication with said first group of fluid conduits, a second chamber in fluid communicawith said second and third groups of fluid conduits and a third chamber in fluid communication with said fourth group of fluid conduits and wherein said plurality of chambers are operable to direct the flow of said first fluid through said groups of fluid conduits in predetermined sequence, said other annular baffle including a first chamber in fluid communication with said first and second groups of conduits, a second chamber in fluid communication with said third group of fluid conduits, and a third chamber in fluid communication with said fourth group of fluid conduits, outlet means for directing the first fluid from said heat exchange chamber and communicating with said third chamber of said one annular baffle.
 17. A heat exchanger as defined in claim 16 further including bypass means for bypassing the flow of fluid from said first chamber of said one annular baffle in order to mix cold water with hot water exiting therefrom.
 18. A heat exchanger as defined in claim 16 further including a member movable in response to a demand for said first fluid, and valve means operatively connected with said member and actuated thereby to effect a flow of the first fluid into the outlet chamber which bypasses said fluid conduit means so that cold first fluid is blended with heated first fluid under control of said member.
 19. A heat exchanger as defined in claim 18 wherein said member has a no-flow position in which said valve means is closed and means for directing cold water from said first chamber of said one annular baffle to said third chamber of said one annular baffle when said means is in its no-flow position.
 20. An apparatus for heating water by steam comprising a heat exchanger having a steam chamber, fluid conduit means for directing water through said steam chamber to a hot water outlet chamber, inlet steam conduit means for delivering steam to said steam chamber, a piston member located in said hot water outlet chamber and movable therein in response to a demand for hot water, steam valve means in said inlet steam conduit means for controlling flow of steam into said steam chamber, means for actuating said valve means in response to movement of said piston member, said means including a pin member engageable with said piston member and movable upon movement of the piston member in response to said demand, a lever operatively connected with said pin member and pivotal upon movement of said piston member, and means operatively interconnecting said lever member and said steam valve means for controlling said steam valve means upon movement of said lever.
 21. An apparatus as defined in claim 20 wherein said means operatively interconnecting the lever member and steam valve means comprises a control valve operated by said lever member and for directing water pressure to said steam valve to effect opening of the steam valve upon opening of the control valve.
 22. An apparatus as defined in claim 21 wherein said control valve has means for communicating inlet water pressure thereto and when opened directs said pressure to said steam valve to effect opening thereof.
 23. An apparatus as defined in claim 22 wherein said valve is spring-biased by a first spring means to an open position for directing water pressure to said steam valve means and said piston member through said lever moves said valve means to said closed position and second spring means acting on said piston member urging said piston member to its no-flow position in which said control valve is in its closed position, and means for adjusting said second spring means which acts on said piston.
 24. An apparatus as defined in claim 20 wherein said means operatively interconnecting the lever member and steam valve means comprises a control valve operated by said lever member for directing an adjustablE fluid pressure to said steam valve to effect opening of the steam valve upon opening of the control valve.
 25. An apparatus as defined in claim 24 wherein said steam valve is a differential diaphragm type so that the adjustable fluid pressure produces an adjustable steam pressure to the heat exchanger. 